We propose to develop a new technique for delivering iron chelators to target organs of iron overload. This technique involves a biological carrier, called a "liposome". The main goal of this project is to enhance the removal of iron deposits in patients suffering from iron overload due to repeated blood transfusions, for example, in Cooley's anemia. The iron chelator, desferrioxamine (DF) has been encapsulated within liposomes, and we have compared the pharmacokinetics of nonencapsulated and encapsulated 59Fe-labeled DF after i.v. administration into mice. The uptake of 59Fe-DF by liver, spleen, and bone marrow is significantly increased by liposome encapsulation. Excretion of 59Fe-DF is also much slower. Red blood cells (RBC) labeled with 59Fe and heat denatured were used to label hepatic reticuloendothelial cells as an experimental model for hemochromatosis. A single i.v. injection of 50 mg/kg of Df contained in liposomes with a mean diameter of 0.5 micron m, and given 24 h after 59Fe-RBC was followed by urinary excretion of about 8% injected dose of 59Fe, compared to only 0.4% by mice given nonencapsulated DF. Thus, this new drug delivery system is potentially useful for treatment of iron overload in complications of Cooley's anemia.